| Abstract Scope |
Tri-layer cladding is a candidate technology for developing damage tolerant nuclear fuel rods that can demonstrate both high temperature stability and corrosion resistance. These fuel rods include an inner molybdenum, intermediate niobium, and exterior zirconium layers. Total thickness of the tri-layer wall ranges from 400 to 550-microns. Sealing of these tubes, given the metallurgical compatibility of the cladding layers, presents challenges. To accomplish sealing in a fashion compatible with the functionality of the differing layers, a unique two stage assembly process was developed. This included using a capacitive discharge technology to attach the molybdenum cap to the inner liner, as well as a zirconium one joined to the outer layer. All joining trials were done in an iterative fashion, supported by metallurgical assessments and leak testing. The approach allowed creation of a cladding with a complete molybdenum surface adjacent to the fuel itself, covered in a continuous layer of zirconium to provide corrosion protection in service. Further, metallurgical investigations of completed attachments showed that the developed processing did not disrupt the tri-layer characteristic of the clad product. |